The present invention is a surgical device assembly. More particularly, it is a catheter system which is adapted to provide artificial systemic blood circulation while temporarily arresting the heart and substantially isolating the heart from the systemic circulation in order to perform surgical procedures on the heart.
Various abnormalities of the heart are generally treated by temporarily arresting the heart from beating, isolating the heart from systemic blood circulation, supporting the systemic blood circulation via an external cardiopulmonary bypass pump, and performing surgical operations directly on the stopped heart. This general method is herein referred to as a xe2x80x9ccardiac bypass procedurexe2x80x9d. Examples of such cardiac bypass procedures include, without limitation: coronary artery bypass graft surgery (xe2x80x9cCABGxe2x80x9d); valve replacement surgery; cardiac transplantation surgery; and a procedure known as the xe2x80x9cmazexe2x80x9d procedure wherein conduction blocks are surgically formed in the wall of one or both of the atria in order to prevent atrial fibrillation.
Conventional techniques in performing such xe2x80x9ccardiac bypass proceduresxe2x80x9d generally include cutting through the sternum in the chest cavity using well known xe2x80x9csternotomyxe2x80x9d techniques, spreading open the rib cage, retracting the lungs from the region of the heart, and directly exposing the heart to the surgeon. One of various known cardioplegia agents may be used to temporarily arrest the heart from beating. Further to the bypass procedure, an external cross clamp is generally used to occlude the aorta in the region of the arch between the aortic root and the carotid arteries. With the cross-clamp in this position, both the left heart chambers and the coronary arteries into the heart are isolated from the systemic arterial circulation while the carotid arteries are fed with the blood flow from the bypass pump. In addition, flow from the superior and inferior vena cava is also temporarily diverted from the heart to the pump, usually by externally tying the vena caval walls onto venous pump cannulae.
Minimally Invasive Cardiac Bypass Catheter Systems
Recent advances have been made in the field of xe2x80x9ccardiac bypass proceduresxe2x80x9d which include the use of novel catheter assemblies which are adapted to temporarily arrest and bypass the heart without the need for direct cross-clamping or externally tying the vena cavae. Such assemblies are generally herein referred to by the terms xe2x80x9cminimally invasive catheter bypass systems,xe2x80x9d or derivatives of these terms, and generally include an arterial catheter, which isolates the left heart chambers from systemic arterial circulation beyond the aortic root, and a venous catheter, which isolates the right heart chambers from venous circulation from the vena cavae. Further to the intended meaning, such minimally invasive catheter bypass systems may be used during procedures which otherwise still require a sternotomy in an otherwise xe2x80x9copen chestxe2x80x9d or xe2x80x9copen heartxe2x80x9d procedure which directly exposes the heart, as well as during procedures which otherwise alleviate the need for such sternotomies, such as for example procedures known as xe2x80x9cport accessxe2x80x9d procedures.
One particular example of a previously known xe2x80x9cminimally invasive cardiac bypass systemxe2x80x9d uses an arterial catheter which occludes the aorta from systemic arterial circulation with an inflatable balloon located on the outside surface of the catheter""s distal end portion which is positioned within the aorta. The arterial catheter further includes a cannula with lumens and distal ports which provide for cardioplegia agent delivery and venting of the left ventricle, respectively, while the heart is isolated from systemic circulation with the inflated balloon on the outer surface of the arterial catheter. Further to this known system, a venous catheter is further provided and uses a balloon in each of the superior and inferior vena cava. The venous catheter balloons inflate to occlude these great veins and thereby isolate the right heart chambers from systemic venous blood flow. Moreover, the venous and arterial catheters which combine to form minimally invasive cardiac bypass catheter systems engage to inlet and outlet ports, respectively of a cardiopulmonary bypass pump, which pump may be further considered a part of the overall system. One such known pump which is believed to be particularly usefull in cardiac bypass procedures, including minimally invasive bypass procedures, is known as the xe2x80x9cBioPumpxe2x80x9d, Model Number xe2x80x9cBP80xe2x80x9d, which is available from Medtronic, Inc.
Further to the description for the minimally invasive cardiac bypass system example just provided above, the terms xe2x80x9cproximalxe2x80x9d and xe2x80x9cdistalxe2x80x9d are herein used throughout this disclosure as relative terms. In the context of describing a device or catheter used in such a system, the term xe2x80x9cproximal,xe2x80x9d such as in the phrase xe2x80x9cproximal endxe2x80x9d, is herein intended to mean toward or closer to a user such as a physician, whereas the term xe2x80x9cdistal,xe2x80x9d such as in the phrase xe2x80x9cdistal endxe2x80x9d is herein intended to mean away from or further away from the user. However, if and where the terms xe2x80x9cproximalxe2x80x9d and xe2x80x9cdistalxe2x80x9d are herein used in the context of describing anatomical structures of the cardiovascular system or physiological blood flow, the term xe2x80x9cproximalxe2x80x9d is herein intended to mean toward or closer to the heart, whereas the term xe2x80x9cdistalxe2x80x9d is herein intended to mean away from or further from the heart. Furthermore, the terms xe2x80x9cupstreamxe2x80x9d and xe2x80x9cdownstreamxe2x80x9d are also relative terms which may be herein used interchangeably with xe2x80x9cproximalxe2x80x9d or xe2x80x9cdistalxe2x80x9d, respectively, in the anatomical or physiological context just described.
According to the method of using known minimally invasive cardiac bypass catheter systems such as the example summarized above, the heart is usually put on xe2x80x9cpartial bypassxe2x80x9d prior to xe2x80x9ccomplete bypassxe2x80x9d. The terms xe2x80x9cpartial bypassxe2x80x9d are herein intended to mean a condition wherein the heart is beating and pumping blood throughout the body""s circulation prior to inflating the balloons on the arterial and venous catheters, and wherein some blood is also aspirated from the vena cavae through the venous catheter, sent through the cardiopulmonary bypass pump, and infused into the arterial circulation through the flow ports along the arterial catheter. The terms xe2x80x9ccomplete bypassxe2x80x9d or xe2x80x9cfull bypassxe2x80x9d or derivatives thereof are therefore herein intended to mean a condition wherein the heart is substantially isolated from systemic venous and arterial circulation by means provided by the venous and arterial catheters, respectively, such as for example by inflating balloons on the exterior surfaces of such venous and arterial catheters to thereby totally occlude the vena cavae and aorta, also respectively, as described above.
According to these definitions for partial and full bypass just provided, a patient is therefore put on partial bypass by first positioning the venous and arterial catheters at respectively predetermined locations along the vena cavae and aorta, respectively, such that the respective flow ports may provide for the respective aspiration or infusion of blood and such that balloons on the catheter outer surfaces may be thereafter inflated to isolate the right and left heart chambers, also respectively, during fill bypass. The procedure for subsequently weaning a patient from partial bypass to full bypass according to the known minimally invasive cardiac bypass system example described above generally proceeds as follows.
Cardioplegia agent is delivered during partial bypass in order to begin reducing the cardiac function ultimately toward the temporarily arrested state. The external balloons are inflated to occlude the vena cavae and isolate the right heart from systemic venous circulation prior to inflating the arterial catheter""s balloon to isolate the left heart from systemic arterial lo circulation. During this xe2x80x9cweaningxe2x80x9d period, the bypass pump circulates the blood aspirated from the vena cavae while the heart continues to pump a declining volume of residual blood from the coronary sinus, right heart chambers, pulmonary circulation (including lungs), and left heart chambers. As the residual volume of blood pumping through the heart declines, and as the cardiac function continues toward temporary arrest under cardioplegia effects, the balloon on the exterior surface of the arterial catheter is then inflated to occlude the aorta and finally achieve full or complete bypass.
Upon inflating the arterial balloon and totally occluding the aorta during the xe2x80x9cweaningxe2x80x9d period onto full bypass as just described, additional cardioplegia agent delivery continues distally of the inflated balloon. However, it has been observed that xe2x80x9cback pressurexe2x80x9d on the cardioplegia delivery cannula during cardioplegia agent delivery, together with the pressure from the beating heart against the totally occluded aorta, may push the arterial balloon downstream along the aorta. As a result, a user may be required to reposition the balloon at the initially desired location along the ascending aorta between the aortic root and the carotid arteries. It is believed that the repositioning of the arterial balloon in response to this pressure response may be performed while the balloon is inflated, or during subsequent iterations of positioning and then inflating in order to adjust for the observed post-inflation movement.
Still further to the known xe2x80x9cminimally invasive cardiac bypass systems,xe2x80x9d weaning a patient off of xe2x80x9ccomplete bypassxe2x80x9d and off of the cardiopulmonary bypass pump while reestablishing physiological cardiac output generally requires deflation of the external balloon on the external surfaces of the arterial and venous catheters. However, some patients have been observed to present complications while cardiac function is being reestablished, which complications may require returning the patient back to a full bypass condition. Therefore, patients are generally kept in surgery for a prolonged period of time subsequent to deflating the balloons on the bypass system catheters and after reestablishing the cardiac function in order to observe the heart""s recovery. In cases where such patients are required to be put back onto cardiac bypass, the balloons must be repositioned at their desired location and then reinflated to isolate the heart. Particularly regarding the occlusion balloon on the external surface of the arterial catheter, this reinflation while the heart is pumping may present the same repositioning issues as previously described above.
It is further believed that the arterial balloon repositioning which may be required during use of arterial catheters according to the known minimally invasive cardiac bypass systems may present a cumbersome and potentially dangerous detriment to the efficiency and safety of the overall minimally invasive cardiac bypass procedure.
There is a need for a minimally invasive cardiac bypass system which includes an arterial catheter with an external balloon which is adapted to inflate and engage the aortic wall to secure the catheter at a predetermined location along the ascending aorta between the aortic root and the carotid arteries along the aortic arch and which is further adapted such that the external balloon does not substantially reposition during such inflation while cardioplegia agent is being delivered to the heart through a cardioplegia cannula upstream from the external balloon or while the heart is beating such as when a patient is being weaned onto partial or full cardiac bypass.
There is also a need for a minimally invasive cardiac bypass system which includes an arterial catheter with an external balloon which is adapted to remain inflated and engaged to the aortic wall at a predetermined location along the ascending aorta while cardiac function is being reestablished as a patient is weaned off of a cardiopulmonary bypass pump subsequent to a surgical cardiac procedure.
There is also a need for a minimally invasive cardiac bypass system which includes an arterial catheter that is adapted to: anchor within the ascending aorta; shunt antegrade aortic blood flow from the aortic root, proximally through a flow lumen within the catheter past the anchor, and into the systemic arterial circulation downstream of the anchor while the heart is still beating during partial cardiac bypass; selectively occlude the shunted antegrade flow path, thereby isolating the aortic root from systemic circulation when the heart is temporarily arrested and on full cardiac bypass; and selectively provide a retrograde flow path through the internal flow lumen of the catheter for active infusion of oxygenated blood from a bypass pump and into the systemic arterial circulation proximally of the anchor when the heart is temporarily arrested during full cardiac bypass.
There is also a need for a minimally invasive cardiac bypass system which includes an arterial catheter which is adapted to shunt antegrade aortic blood flow before or during partial cardiac bypass from the aortic root, through a distal flow port into an internal flow lumen within the catheter, and out of the internal flow lumen through an intermediate flow port into systemic arterial circulation while minimizing hemolysis at the transition region between the aortic root and the distal flow port into the internal flow lumen and also while minimizing the movement of the arterial catheter.
There is also a need for a minimally invasive cardiopulmonary bypass system which includes a venous catheter which is adapted to substantially aspirate the venous blood from the vena cavae while substantially isolating the right ventricle from the vena caval blood flow without circumferentially engaging the interior wall of the inferior or superior vena cavae and without completely occluding the vena cavae.
The present invention is a minimally invasive bypass system which includes an arterial catheter and a venous catheter, each catheter being adapted to couple with a cardiopulmonary bypass pump in order to provide systemic circulation of oxygenated blood while the heart is isolated from the systemic circulation in a substantially bloodless field. The arterial catheter is adapted to wean a patient onto and off of cardiac bypass by using an external shunt valve in combination with internal valves within an internal flow lumen. The external and internal valves of the arterial catheter selectively allow for either: (1) antegrade perfusion of blood flow from a beating heart, proximally through the flow lumen, past an external shunt valve in a closed position within the aorta, out of ports located along the catheter proximally of the external shunt valve, and into the systemic arterial circulation; or (2) active perfusion of oxygenated blood from a cardiopulmonary bypass machine, distally through the flow lumen, and into systemic circulation also through ports located along the catheter proximally of the external shunt valve. The venous catheter is adapted to isolate the right ventricle from venous blood flow and to aspirate the venous blood from the vena cavae without circumferentially engaging the vena cavae with an expanded balloon.
One mode of the invention is a medical device assembly which is adapted for selectively shunting an antegrade flow of blood from an aortic root in an aorta of an animal and into a proximal region of the aorta which is located proximally of the aortic root. The assembly according to this mode includes an elongate body with a flow lumen which extends between a distal flow port, located on the body""s distal end portion, and an intermediate flow port located along the elongate body proximally of the distal flow port.
In one aspect of this mode, an external shunt valve is located along distal end portion between the distal and intermediate flow ports. The external shunt valve includes an anchor and a funnel and is adjustable between an open position and a shunting position. In the open position the anchor and funnel are adapted to allow the antegrade blood flow to pass through an exterior space between the distal end portion of the elongate body and the aortic wall. In the shunting position the anchor is adapted to radially engage the aortic wall such that the distal end portion of the elongate body is secured at a predetermined location within the aorta. The funnel in the shunting position is adapted to substantially shunt the antegrade blood flow from the aortic root and into the flow lumen through the distal flow port while substantially isolating the exterior space around the catheter from that antegrade flow.
In one variation of this aspect, the external shunt valve is an expandable member that is adjustable from a radially collapsed condition to a radially expanded condition which forms the anchor and the funnel. The funnel includes a proximally reducing, tapered inner diameter from a large inner diameter portion to a reduced inner diameter portion which is located adjacent to the distal flow port. Further to this aspect, the expandable member may be an inflatable balloon which has an expanded shape that forms the anchor and the funnel.
In another aspect of this mode, a distal internal valve is coupled to the flow lumen between the distal and intermediate flow ports. In an open position, the distal internal valve is adapted to allow for fluid to flow through the flow lumen between the distal and intermediate flow ports. In a closed position, the distal internal valve is adapted to substantially isolate the distal flow port from the intermediate flow port through the flow lumen.
In one variation of this aspect, the distal internal valve is an expandable balloon which is adapted to selectively occlude the flow lumen when pressurized and adjusted to a radially expanded condition. The balloon may be located within the flow lumen, or may be located adjacent to a collapsible tubular member which forms at least a portion of the flow lumen. In the latter variation, expansion of the balloon collapses the collapsible tubular member to occlude flow therethrough.
In another variation of this aspect, the flow lumen further communicates externally of the elongate body through a proximal flow port located along the proximal end portion of the elongate body. A proximal internal valve is coupled to the flow lumen between the intermediate flow port and the proximal flow port and is also adjustable between open and closed positions. According to this variation, the distal internal valve may be adjusted to the open position with the proximal internal valve adjusted to the closed position such that antegrade blood flow from the aortic root may be shunted through the flow lumen between the distal and intermediate flow ports while the antegrade flow is isolated from the region of the flow lumen proximally of the proximal internal valve. By alternatively adjusting the distal internal valve to the closed position and the proximal internal valve to the open position, oxygenated blood from a cardiopulmonary bypass pump may be perfused distally through the flow lumen between the proximal and intermediate flow ports while the distal flow is isolated from the flow lumen distally of the intermediate flow port. Still further to this variation, an expandable balloon may be provided for the proximal internal valve.
In another variation of this aspect, an external shunt valve is provided along the distal end portion of the elongate body between the distal and intermediate flow ports and is adjustable between an open position and a closed position. The external shunt valve in the closed position forms an anchor to secure the valve at a predetermined location along the aorta and also forms a funnel which is adapted to selectively shunt antegrade flow of blood from the aortic root and into the internal flow lumen of the catheter through the distal flow port.
In still another variation of this aspect, a plurality of intermediate ports are provided along the elongate body proximally of the external shunt valve and between the distal and proximal flow ports. An intermediate internal valve is provided between each pair of adjacent intermediate ports and is adjustable from an open to a closed position. The distal, intermediate, and proximal internal valves are selectively adjustable to their respective open or closed positions such that a predetermined combination of intermediate ports may be perfused with blood either from the aorta, before isolating the heart from systemic circulation during bypass, or from the cardiopulmonary pump after isolating and stopping the heart during bypass.
Another mode of the invention is a medical device assembly which is adapted to selectively aspirate venous blood flow from the vena cavae while substantially isolating the right ventricle from the vena cavae and also Without circumferentially engaging the interior wall of the vena cavae. The assembly according to this mode includes an elongate body with a proximal end portion, a distal end portion, and a flow lumen which extends between a distal flow port located along the body""s distal end portion and a proximal flow port located along the body""s proximal end portion.
In another aspect of this mode, an external valve is located along the elongate body between the distal and proximal flow ports and is adjustable from an open position to a closed position. The external valve includes a valve member which is positioned at a discrete location around the body""s circumference, which is adjustable from a first radial position to a second, radially displaced position adjacent to the elongate body, and which is further adjustable from a radially collapsed condition to a radially expanded condition when in the radially displaced position. The open position of the external valve is characterized by the first radial position of the valve member which is adapted to allow for the venous blood to flow from the vena cavae and into the right heart chambers. The closed position for the external valve is characterized by aligning the discrete circumferential location of the valve member with the sinus venarum between the vena cavae and the right atrium, thereafter adjusting the valve member to the radially displaced position which is located at least in part within the right atrium, and further adjusting the valve member to the radially expanded condition which is adapted to substantially isolate the right ventricle from the vena cavae. By adjusting the external valve to the closed position and coupling the proximal flow port to an inlet port of a cardiopulmonary bypass pump, blood within the vena cavae may aspirated into the distal flow port, along the internal flow lumen, and into the cardiopulmonary bypass pump.
In one variation of this aspect, the valve member includes two expandable members which are separated by a space. In the radially displaced position the valve member is adapted such that the two expandable members are positioned within the right atrium and right ventricle, respectively, wherein the valve that separates the right atrium and the right ventricle is positioned within the space. When the valve member is adjusted to the radially expanded condition the two expandable members expand to substantially narrow the space therebetween, thereby engaging the valve and isolating the right ventricle from the right atrium.
In another variation of this aspect, an intermediate flow port is located along the elongate body""s distal end portion between the distal and proximal flow ports. The distal flow port is adapted to aspirate blood from the superior vena cava and the intermediate port is adapted to aspirate blood from the inferior vena cava. The distal and intermediate flow ports may communicate with a common venous flow lumen or with separate lumens, respectively.
In another aspect of this mode, an external valve is located along the distal end portion proximally of the distal flow port and is adjustable from a radially collapsed condition, which characterizes an open position, and a radially expanded condition, which characterizes a closed position. The external valve when in the closed position has an outer diameter which is slightly less than the inner diameter of the vena cava wall such that the external valve does not circumferentially engage the.vena cava and venous blood is only partially occluded through the vena cava. The external valve is thus adapted as a pressure cuff to increase the pressure in the region of the distal flow port to enhance the aspiration of that blood through that port, through the flow lumen, and into a cardiopulmonary bypass pump.
In one variation of this aspect, a distal flow lumen extends between the distal flow port and a first proximal flow port on the body""s proximal end portion, and an intermediate flow lumen extends between an intermediate flow port, located along the distal end portion proximally of the external shunt valve, and a second proximal flow port also located along the body""s proximal end portion. In a further variation, two external valves are providedxe2x80x94a distal external valve is located along the elongate body proximally adjacent to the distal flow port, and an intermediate external valve is located along the elongate body between the distal external valve and the intermediate flow port. The distal external valve is adapted for positioning within the superior vena cava between the distal flow port and the sinus venarum into the right atrium, while the intermediate external valve is adapted to be positioned within the inferior vena cava between the sinus venarum and the intermediate flow port. By adjusting the external valves to their respectively closed positions, venous blood flow is shunted from the vena cavae and into a cardiopulmonary bypass pump through the distal and intermediate flow lumens while the right heart chambers are substantially isolated from the venous flow. In still a further variation, a leakage port is also provided between the distal and intermediate external valves and may communicate proximally to an aspiration pump through its own lumen or through a shared lumen with either or both of the distal and intermediate flow ports.
Another mode of the invention is a method for isolating the left ventricle and aortic root of a mammalian heart from systemic arterial circulation during a cardiopulmonary bypass procedure. The method according to this mode includes positioning a distal end portion of an arterial catheter at a predetermined location within the aortic root; anchoring the distal end portion at the predetermined position; and shunting antegrade aortic blood flow from the aortic root to a proximal region of the aorta proximally of the predetermined position while isolating the antegrade aortic blood flow from an exterior space between the cannula and the aortic wall and also between the predetermined position and the proximal region.
One aspect of this method further includes shunting the antegrade aortic blood flow into an interior flow lumen which extends through the arterial catheter between a distal flow port located within the aortic root and an intermediate flow port located along the distal end portion of the elongate body proximally of the predetermined position.
One variation of this aspect includes adjusting an external shunt valve, which is located between the distal and intermediate flow ports, from a radially collapsed condition to a radially expanded condition that circumferentially engages the aortic wall and thereby substantially isolates the exterior space around the cannula from the antegrade aortic blood flow. This variation may further include funneling the antegrade blood flow from the aortic root and into the distal flow port of the flow lumen through a funnel formed by the external shunt valve.
Another variation of this aspect includes selectively preventing the antegrade aortic flow from passing through the flow lumen proximally of the intermediate flow port by selectively occluding the flow lumen between the intermediate flow port and a proximal flow port located along the proximal end portion of the catheter. This variation further includes adjusting a proximal internal valve located between the intermediate and proximal flow ports from an open position, which is adapted to substantially allow for flow through the flow lumen between the intermediate and proximal flow ports, to a closed position, which is adapted to substantially occlude flow between the intermediate and proximal flow ports.
Still a further variation of this aspect includes selectively preventing the antegrade aortic flow from passing through the flow lumen between the distal and intermediate flow ports adjusting an intermediate internal valve coupled to the flow lumen between the distal and intermediate flow ports to a closed position, thereby substantially occluding flow through the flow lumen between the distal and intermediate flow ports. This aspect further includes adjusting a proximal internal valve located between the intermediate and proximal flow ports to an open position, which is adapted to substantially allow for flow through the flow lumen between the intermediate and proximal flow ports. This aspect also further includes perfusing oxygenated blood through the intermediate flow port from a cardiopulmonary bypass pump which is coupled to the proximal flow port.